drivers/serial/altera_uart.c

   1 /*
   2  * altera_uart.c -- Altera UART driver
   3  *
   4  * Based on mcf.c -- Freescale ColdFire UART driver
   5  *
   6  * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
   7  * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
   8  * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/timer.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/module.h>
  21 #include <linux/console.h>
  22 #include <linux/tty.h>
  23 #include <linux/tty_flip.h>
  24 #include <linux/serial.h>
  25 #include <linux/serial_core.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/io.h>
  28 #include <linux/altera_uart.h>
  29
  30 #define DRV_NAME "altera_uart"
  31 #define SERIAL_ALTERA_MAJOR 204
  32 #define SERIAL_ALTERA_MINOR 213
  33
  34 /*
  35  * Altera UART register definitions according to the Nios UART datasheet:
  36  * http://www.altera.com/literature/ds/ds_nios_uart.pdf
  37  */
  38
  39 #define ALTERA_UART_SIZE                32
  40
  41 #define ALTERA_UART_RXDATA_REG          0
  42 #define ALTERA_UART_TXDATA_REG          4
  43 #define ALTERA_UART_STATUS_REG          8
  44 #define ALTERA_UART_CONTROL_REG         12
  45 #define ALTERA_UART_DIVISOR_REG         16
  46 #define ALTERA_UART_EOP_REG             20
  47
  48 #define ALTERA_UART_STATUS_PE_MSK       0x0001  /* parity error */
  49 #define ALTERA_UART_STATUS_FE_MSK       0x0002  /* framing error */
  50 #define ALTERA_UART_STATUS_BRK_MSK      0x0004  /* break */
  51 #define ALTERA_UART_STATUS_ROE_MSK      0x0008  /* RX overrun error */
  52 #define ALTERA_UART_STATUS_TOE_MSK      0x0010  /* TX overrun error */
  53 #define ALTERA_UART_STATUS_TMT_MSK      0x0020  /* TX shift register state */
  54 #define ALTERA_UART_STATUS_TRDY_MSK     0x0040  /* TX ready */
  55 #define ALTERA_UART_STATUS_RRDY_MSK     0x0080  /* RX ready */
  56 #define ALTERA_UART_STATUS_E_MSK        0x0100  /* exception condition */
  57 #define ALTERA_UART_STATUS_DCTS_MSK     0x0400  /* CTS logic-level change */
  58 #define ALTERA_UART_STATUS_CTS_MSK      0x0800  /* CTS logic state */
  59 #define ALTERA_UART_STATUS_EOP_MSK      0x1000  /* EOP written/read */
  60
  61                                                 /* Enable interrupt on... */
  62 #define ALTERA_UART_CONTROL_PE_MSK      0x0001  /* ...parity error */
  63 #define ALTERA_UART_CONTROL_FE_MSK      0x0002  /* ...framing error */
  64 #define ALTERA_UART_CONTROL_BRK_MSK     0x0004  /* ...break */
  65 #define ALTERA_UART_CONTROL_ROE_MSK     0x0008  /* ...RX overrun */
  66 #define ALTERA_UART_CONTROL_TOE_MSK     0x0010  /* ...TX overrun */
  67 #define ALTERA_UART_CONTROL_TMT_MSK     0x0020  /* ...TX shift register empty */
  68 #define ALTERA_UART_CONTROL_TRDY_MSK    0x0040  /* ...TX ready */
  69 #define ALTERA_UART_CONTROL_RRDY_MSK    0x0080  /* ...RX ready */
  70 #define ALTERA_UART_CONTROL_E_MSK       0x0100  /* ...exception*/
  71
  72 #define ALTERA_UART_CONTROL_TRBK_MSK    0x0200  /* TX break */
  73 #define ALTERA_UART_CONTROL_DCTS_MSK    0x0400  /* Interrupt on CTS change */
  74 #define ALTERA_UART_CONTROL_RTS_MSK     0x0800  /* RTS signal */
  75 #define ALTERA_UART_CONTROL_EOP_MSK     0x1000  /* Interrupt on EOP */
  76
  77 /*
  78  * Local per-uart structure.
  79  */
  80 struct altera_uart {
  81         struct uart_port port;
  82         struct timer_list tmr;
  83         unsigned int sigs;      /* Local copy of line sigs */
  84         unsigned short imr;     /* Local IMR mirror */
  85 };
  86
  87 static u32 altera_uart_readl(struct uart_port *port, int reg)
  88 {
  89         struct altera_uart_platform_uart *platp = port->private_data;
  90
  91         return readl(port->membase + (reg << platp->bus_shift));
  92 }
  93
  94 static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
  95 {
  96         struct altera_uart_platform_uart *platp = port->private_data;
  97
  98         writel(dat, port->membase + (reg << platp->bus_shift));
  99 }
 100
 101 static unsigned int altera_uart_tx_empty(struct uart_port *port)
 102 {
 103         return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 104                 ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
 105 }
 106
 107 static unsigned int altera_uart_get_mctrl(struct uart_port *port)
 108 {
 109         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 110         unsigned int sigs;
 111
 112         sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 113              ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
 114         sigs |= (pp->sigs & TIOCM_RTS);
 115
 116         return sigs;
 117 }
 118
 119 static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
 120 {
 121         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 122
 123         pp->sigs = sigs;
 124         if (sigs & TIOCM_RTS)
 125                 pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
 126         else
 127                 pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
 128         altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 129 }
 130
 131 static void altera_uart_start_tx(struct uart_port *port)
 132 {
 133         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 134
 135         pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
 136         altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 137 }
 138
 139 static void altera_uart_stop_tx(struct uart_port *port)
 140 {
 141         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 142
 143         pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 144         altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 145 }
 146
 147 static void altera_uart_stop_rx(struct uart_port *port)
 148 {
 149         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 150
 151         pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
 152         altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 153 }
 154
 155 static void altera_uart_break_ctl(struct uart_port *port, int break_state)
 156 {
 157         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 158         unsigned long flags;
 159
 160         spin_lock_irqsave(&port->lock, flags);
 161         if (break_state == -1)
 162                 pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
 163         else
 164                 pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
 165         altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 166         spin_unlock_irqrestore(&port->lock, flags);
 167 }
 168
 169 static void altera_uart_enable_ms(struct uart_port *port)
 170 {
 171 }
 172
 173 static void altera_uart_set_termios(struct uart_port *port,
 174                                     struct ktermios *termios,
 175                                     struct ktermios *old)
 176 {
 177         unsigned long flags;
 178         unsigned int baud, baudclk;
 179
 180         baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 181         baudclk = port->uartclk / baud;
 182
 183         if (old)
 184                 tty_termios_copy_hw(termios, old);
 185         tty_termios_encode_baud_rate(termios, baud, baud);
 186
 187         spin_lock_irqsave(&port->lock, flags);
 188         uart_update_timeout(port, termios->c_cflag, baud);
 189         altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
 190         spin_unlock_irqrestore(&port->lock, flags);
 191 }
 192
 193 static void altera_uart_rx_chars(struct altera_uart *pp)
 194 {
 195         struct uart_port *port = &pp->port;
 196         unsigned char ch, flag;
 197         unsigned short status;
 198
 199         while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
 200                ALTERA_UART_STATUS_RRDY_MSK) {
 201                 ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
 202                 flag = TTY_NORMAL;
 203                 port->icount.rx++;
 204
 205                 if (status & ALTERA_UART_STATUS_E_MSK) {
 206                         altera_uart_writel(port, status,
 207                                            ALTERA_UART_STATUS_REG);
 208
 209                         if (status & ALTERA_UART_STATUS_BRK_MSK) {
 210                                 port->icount.brk++;
 211                                 if (uart_handle_break(port))
 212                                         continue;
 213                         } else if (status & ALTERA_UART_STATUS_PE_MSK) {
 214                                 port->icount.parity++;
 215                         } else if (status & ALTERA_UART_STATUS_ROE_MSK) {
 216                                 port->icount.overrun++;
 217                         } else if (status & ALTERA_UART_STATUS_FE_MSK) {
 218                                 port->icount.frame++;
 219                         }
 220
 221                         status &= port->read_status_mask;
 222
 223                         if (status & ALTERA_UART_STATUS_BRK_MSK)
 224                                 flag = TTY_BREAK;
 225                         else if (status & ALTERA_UART_STATUS_PE_MSK)
 226                                 flag = TTY_PARITY;
 227                         else if (status & ALTERA_UART_STATUS_FE_MSK)
 228                                 flag = TTY_FRAME;
 229                 }
 230
 231                 if (uart_handle_sysrq_char(port, ch))
 232                         continue;
 233                 uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
 234                                  flag);
 235         }
 236
 237         tty_flip_buffer_push(port->state->port.tty);
 238 }
 239
 240 static void altera_uart_tx_chars(struct altera_uart *pp)
 241 {
 242         struct uart_port *port = &pp->port;
 243         struct circ_buf *xmit = &port->state->xmit;
 244
 245         if (port->x_char) {
 246                 /* Send special char - probably flow control */
 247                 altera_uart_writel(port, port->x_char, ALTERA_UART_TXDATA_REG);
 248                 port->x_char = 0;
 249                 port->icount.tx++;
 250                 return;
 251         }
 252
 253         while (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 254                ALTERA_UART_STATUS_TRDY_MSK) {
 255                 if (xmit->head == xmit->tail)
 256                         break;
 257                 altera_uart_writel(port, xmit->buf[xmit->tail],
 258                        ALTERA_UART_TXDATA_REG);
 259                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 260                 port->icount.tx++;
 261         }
 262
 263         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 264                 uart_write_wakeup(port);
 265
 266         if (xmit->head == xmit->tail) {
 267                 pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 268                 altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 269         }
 270 }
 271
 272 static irqreturn_t altera_uart_interrupt(int irq, void *data)
 273 {
 274         struct uart_port *port = data;
 275         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 276         unsigned int isr;
 277
 278         isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;
 279
 280         spin_lock(&port->lock);
 281         if (isr & ALTERA_UART_STATUS_RRDY_MSK)
 282                 altera_uart_rx_chars(pp);
 283         if (isr & ALTERA_UART_STATUS_TRDY_MSK)
 284                 altera_uart_tx_chars(pp);
 285         spin_unlock(&port->lock);
 286
 287         return IRQ_RETVAL(isr);
 288 }
 289
 290 static void altera_uart_timer(unsigned long data)
 291 {
 292         struct uart_port *port = (void *)data;
 293         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 294
 295         altera_uart_interrupt(0, port);
 296         mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
 297 }
 298
 299 static void altera_uart_config_port(struct uart_port *port, int flags)
 300 {
 301         port->type = PORT_ALTERA_UART;
 302
 303         /* Clear mask, so no surprise interrupts. */
 304         altera_uart_writel(port, 0, ALTERA_UART_CONTROL_REG);
 305         /* Clear status register */
 306         altera_uart_writel(port, 0, ALTERA_UART_STATUS_REG);
 307 }
 308
 309 static int altera_uart_startup(struct uart_port *port)
 310 {
 311         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 312         unsigned long flags;
 313         int ret;
 314
 315         if (!port->irq) {
 316                 setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
 317                 mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
 318                 return 0;
 319         }
 320
 321         ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
 322                         DRV_NAME, port);
 323         if (ret) {
 324                 pr_err(DRV_NAME ": unable to attach Altera UART %d "
 325                        "interrupt vector=%d\n", port->line, port->irq);
 326                 return ret;
 327         }
 328
 329         spin_lock_irqsave(&port->lock, flags);
 330
 331         /* Enable RX interrupts now */
 332         pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
 333         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 334
 335         spin_unlock_irqrestore(&port->lock, flags);
 336
 337         return 0;
 338 }
 339
 340 static void altera_uart_shutdown(struct uart_port *port)
 341 {
 342         struct altera_uart *pp = container_of(port, struct altera_uart, port);
 343         unsigned long flags;
 344
 345         spin_lock_irqsave(&port->lock, flags);
 346
 347         /* Disable all interrupts now */
 348         pp->imr = 0;
 349         writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
 350
 351         spin_unlock_irqrestore(&port->lock, flags);
 352
 353         if (port->irq)
 354                 free_irq(port->irq, port);
 355         else
 356                 del_timer_sync(&pp->tmr);
 357 }
 358
 359 static const char *altera_uart_type(struct uart_port *port)
 360 {
 361         return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
 362 }
 363
 364 static int altera_uart_request_port(struct uart_port *port)
 365 {
 366         /* UARTs always present */
 367         return 0;
 368 }
 369
 370 static void altera_uart_release_port(struct uart_port *port)
 371 {
 372         /* Nothing to release... */
 373 }
 374
 375 static int altera_uart_verify_port(struct uart_port *port,
 376                                    struct serial_struct *ser)
 377 {
 378         if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
 379                 return -EINVAL;
 380         return 0;
 381 }
 382
 383 /*
 384  *      Define the basic serial functions we support.
 385  */
 386 static struct uart_ops altera_uart_ops = {
 387         .tx_empty       = altera_uart_tx_empty,
 388         .get_mctrl      = altera_uart_get_mctrl,
 389         .set_mctrl      = altera_uart_set_mctrl,
 390         .start_tx       = altera_uart_start_tx,
 391         .stop_tx        = altera_uart_stop_tx,
 392         .stop_rx        = altera_uart_stop_rx,
 393         .enable_ms      = altera_uart_enable_ms,
 394         .break_ctl      = altera_uart_break_ctl,
 395         .startup        = altera_uart_startup,
 396         .shutdown       = altera_uart_shutdown,
 397         .set_termios    = altera_uart_set_termios,
 398         .type           = altera_uart_type,
 399         .request_port   = altera_uart_request_port,
 400         .release_port   = altera_uart_release_port,
 401         .config_port    = altera_uart_config_port,
 402         .verify_port    = altera_uart_verify_port,
 403 };
 404
 405 static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];
 406
 407 #if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
 408
 409 int __init early_altera_uart_setup(struct altera_uart_platform_uart *platp)
 410 {
 411         struct uart_port *port;
 412         int i;
 413
 414         for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS && platp[i].mapbase; i++) {
 415                 port = &altera_uart_ports[i].port;
 416
 417                 port->line = i;
 418                 port->type = PORT_ALTERA_UART;
 419                 port->mapbase = platp[i].mapbase;
 420                 port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
 421                 port->iotype = SERIAL_IO_MEM;
 422                 port->irq = platp[i].irq;
 423                 port->uartclk = platp[i].uartclk;
 424                 port->flags = UPF_BOOT_AUTOCONF;
 425                 port->ops = &altera_uart_ops;
 426                 port->private_data = platp;
 427         }
 428
 429         return 0;
 430 }
 431
 432 static void altera_uart_console_putc(struct uart_port *port, const char c)
 433 {
 434         while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 435                  ALTERA_UART_STATUS_TRDY_MSK))
 436                 cpu_relax();
 437
 438         writel(c, port->membase + ALTERA_UART_TXDATA_REG);
 439 }
 440
 441 static void altera_uart_console_write(struct console *co, const char *s,
 442                                       unsigned int count)
 443 {
 444         struct uart_port *port = &(altera_uart_ports + co->index)->port;
 445
 446         for (; count; count--, s++) {
 447                 altera_uart_console_putc(port, *s);
 448                 if (*s == '\n')
 449                         altera_uart_console_putc(port, '\r');
 450         }
 451 }
 452
 453 static int __init altera_uart_console_setup(struct console *co, char *options)
 454 {
 455         struct uart_port *port;
 456         int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
 457         int bits = 8;
 458         int parity = 'n';
 459         int flow = 'n';
 460
 461         if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
 462                 return -EINVAL;
 463         port = &altera_uart_ports[co->index].port;
 464         if (!port->membase)
 465                 return -ENODEV;
 466
 467         if (options)
 468                 uart_parse_options(options, &baud, &parity, &bits, &flow);
 469
 470         return uart_set_options(port, co, baud, parity, bits, flow);
 471 }
 472
 473 static struct uart_driver altera_uart_driver;
 474
 475 static struct console altera_uart_console = {
 476         .name   = "ttyAL",
 477         .write  = altera_uart_console_write,
 478         .device = uart_console_device,
 479         .setup  = altera_uart_console_setup,
 480         .flags  = CON_PRINTBUFFER,
 481         .index  = -1,
 482         .data   = &altera_uart_driver,
 483 };
 484
 485 static int __init altera_uart_console_init(void)
 486 {
 487         register_console(&altera_uart_console);
 488         return 0;
 489 }
 490
 491 console_initcall(altera_uart_console_init);
 492
 493 #define ALTERA_UART_CONSOLE     (&altera_uart_console)
 494
 495 #else
 496
 497 #define ALTERA_UART_CONSOLE     NULL
 498
 499 #endif /* CONFIG_ALTERA_UART_CONSOLE */
 500
 501 /*
 502  *      Define the altera_uart UART driver structure.
 503  */
 504 static struct uart_driver altera_uart_driver = {
 505         .owner          = THIS_MODULE,
 506         .driver_name    = DRV_NAME,
 507         .dev_name       = "ttyAL",
 508         .major          = SERIAL_ALTERA_MAJOR,
 509         .minor          = SERIAL_ALTERA_MINOR,
 510         .nr             = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
 511         .cons           = ALTERA_UART_CONSOLE,
 512 };
 513
 514 static int __devinit altera_uart_probe(struct platform_device *pdev)
 515 {
 516         struct altera_uart_platform_uart *platp = pdev->dev.platform_data;
 517         struct uart_port *port;
 518         struct resource *res_mem;
 519         struct resource *res_irq;
 520         int i = pdev->id;
 521
 522         /* -1 emphasizes that the platform must have one port, no .N suffix */
 523         if (i == -1)
 524                 i = 0;
 525
 526         if (i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
 527                 return -EINVAL;
 528
 529         port = &altera_uart_ports[i].port;
 530
 531         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 532         if (res_mem)
 533                 port->mapbase = res_mem->start;
 534         else if (platp->mapbase)
 535                 port->mapbase = platp->mapbase;
 536         else
 537                 return -EINVAL;
 538
 539         res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 540         if (res_irq)
 541                 port->irq = res_irq->start;
 542         else if (platp->irq)
 543                 port->irq = platp->irq;
 544
 545         port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
 546         if (!port->membase)
 547                 return -ENOMEM;
 548
 549         port->line = i;
 550         port->type = PORT_ALTERA_UART;
 551         port->iotype = SERIAL_IO_MEM;
 552         port->uartclk = platp->uartclk;
 553         port->ops = &altera_uart_ops;
 554         port->flags = UPF_BOOT_AUTOCONF;
 555         port->private_data = platp;
 556
 557         uart_add_one_port(&altera_uart_driver, port);
 558
 559         return 0;
 560 }
 561
 562 static int __devexit altera_uart_remove(struct platform_device *pdev)
 563 {
 564         struct uart_port *port = &altera_uart_ports[pdev->id].port;
 565
 566         uart_remove_one_port(&altera_uart_driver, port);
 567         return 0;
 568 }
 569
 570 static struct platform_driver altera_uart_platform_driver = {
 571         .probe  = altera_uart_probe,
 572         .remove = __devexit_p(altera_uart_remove),
 573         .driver = {
 574                 .name   = DRV_NAME,
 575                 .owner  = THIS_MODULE,
 576                 .pm     = NULL,
 577         },
 578 };
 579
 580 static int __init altera_uart_init(void)
 581 {
 582         int rc;
 583
 584         rc = uart_register_driver(&altera_uart_driver);
 585         if (rc)
 586                 return rc;
 587         rc = platform_driver_register(&altera_uart_platform_driver);
 588         if (rc) {
 589                 uart_unregister_driver(&altera_uart_driver);
 590                 return rc;
 591         }
 592         return 0;
 593 }
 594
 595 static void __exit altera_uart_exit(void)
 596 {
 597         platform_driver_unregister(&altera_uart_platform_driver);
 598         uart_unregister_driver(&altera_uart_driver);
 599 }
 600
 601 module_init(altera_uart_init);
 602 module_exit(altera_uart_exit);
 603
 604 MODULE_DESCRIPTION("Altera UART driver");
 605 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 606 MODULE_LICENSE("GPL");
 607 MODULE_ALIAS("platform:" DRV_NAME);
 608 MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);